We are attempting to classify from a clinical, immunohistologic and biochemical point of view a group of diseases characterized by the deposition of amyloid fibrils. The amyloidosis are a heterogeneous group of diseases, genetic, idiopathic, and secondary, all of which have in common abnormal protein deposition in the form of Beta-pleated sheet fibrils. Amyloid fibrils are relatively resistant to solution in physiological solvents and to normal proteolytic digestion. The latter characteristic leads to the relentless deposition and accumulation of these relative inert fibrils in tissues causing atrophy and death as the result of interference with the normal physiological process of the afected organ. Amyloid fibrils share physico-chemical properties by which they are identified. However, each amyloid protein consists of an insoluble polymer which has risen by cleavage of a different precursor. We believe that all types of amyloidosis occur in the face of the production (or overproduction) of a soluble precursor in patients who are genetically or otherwise defective in degrading these molecules. Our goal is 1) to isolate and characterize the amyloid found in some heredofamilial types of amyloidosis e.g. Heriditary Cerebral Hemmorrhage With Amyloidosis (HCHWA) and Familial Amyloidotic Polyneuropathy (FAP) and the amyloid found in Alzheimer's Disease (AD); 2) to isolate their soluble precursors and to understand the mechanism of amyloid formation and deposition; and 3) to study the biological function and structure of serum amyloid P (SAP) and tissue amyloid P (AP) which is an obligatory constituent of all types of amyloid.